Not Applicable
The present invention relates generally to portable lights incorporating a lamp and an electrical power source. More specifically, the present invention relates to portable illumination of aircraft cockpit instruments using light emitting diodes (LEDs).
Modern aircraft are equipped with a light source for illumination of cockpit instruments for use during nighttime and low ambient light conditions. Illumination is usually performed by small incandescent lamps integrated into the instruments or instrument panel. These small laps provide sufficient illumination of the cockpit instruments and their luminance is sometimes adjustable. Small general aviation aircraft built in the past however, have little or no cockpit instrument illumination available. Their instruments or instrument panels are not equipped with integral lamps, and illumination is sometimes provided only by a single incandescent lamp usually mounted onto the overhead ceiling of the cockpit. The purpose of the single lamp is for providing a flood lamp effect over the entire instrument panel. However, due to the overhead location of the light source found on most small general aviation aircraft, the pilot and the steering or control yokes usually block the flood beam. This causes shadows or dark areas on the instrument panel, and as a result, visual scanning of all cockpit instruments in a normal sequence is interrupted since time is required for the pilot""s eyes to adjust to the difference in instrument illumination. In an attempt to prevent night blindness and improve night vision, prior art also incorporates a red filter lens into the overhead lamp assembly. A drawback of the red lens, however, greatly reduces the luminance of the instrument panel. Aircraft manufacturers recognized this design flaw and have greatly improved cockpit illumination with various prior art methods such as integrating multiple lamps into the instruments, thus eliminating any shadows or dark areas on the instrument panel.
The following prior art references relate to modem aircraft with integral panel lights, and do not apply to older aircraft that employ a flood beam method for panel illumination. U.S. Pat. No. 5,023,763 to LeGras (1991) provides for an illuminated panel display, and U.S. Pat No. 4,710,858 to Van Hout et al. (1987) provides for ligted panel display switches. U.S. Pat No. 4,217,625 to Klein (1980) provides for lighted sent dial faceplates using integral LEDs, and U.S. Pat. No. 4,977,486 to Gotoh (1990) provides for a method of illuminating displays using a light guiding member similar to a light pipe. U.S. Pat No. 5,140,472 to Langer et al. (1992) provides for a passive prism device for direct daylight viewing of cockpit instruments. There are however, many older aircraft presently operating today that were manufactured before any design improvements were incorporated. The following prior art patents attempt to compensate for the single overhead light assembly without employing integral panel lights or inter panel lighting methods, but only provide partial instrument panel illumination. U.S. Pat. No. 5,031,080 to Aikens et al. (1991) provides for a flashlight with a rotating filter used in conjunction with night vision equipment, and U.S. Pat. No. 5,353,205 to Hudak (1994) provides for a helmet mounted or detachable flashlight used in conjunction with night vision equipment U.S. Pat. No. 5,083,246 to Lamert (1992) provides for a single helmet mounted LED, and U.S. Pat. No. 5,124,892 to Lambert (1992) provides for a hand mounted LED.
Most pilots of older aircraft have lined to compensate with the drawbacks of the flood lamp illumination method by carrying a backup flashlight or similar prior art during nighttime and low light level conditions. This enables the pilot to scan the darker areas of the instrument panel, but requires the pilot use a free hand to scan and operate the flashlight. This practice can place the pilot in a dangerous situation, especially during the landing and takeoff phases of flight where both hands are required to operate multiple tasks such as instrument scanning, throttle control, radio communications, and operation of flaps and landing gear. In prior art methods where helmet or hand mounted light sources are used, repetitive head or hand movements are required in order to scan an panel instruments. The repetitive head or hand movements result in pilot fatigue. Although U.S. Pat. No. 4,580,196 to Task (1986) provides for an even illumination of cockpit panel instruments in conjunction with night vision equipment through the use of multiple LED arrays, it does not provide for a backup illumination method in the event of an emergency when all cockpit lights have failed. It is common aviation knowledge that a loss of cockpit panel illumination even for only a moment can place the pilot into spatial disorientation whereby the pilot is disoriented and unable to fly without any instruments or outside visual cues for reference. Prior art methods provide a supplement to the overhead light assembly method, but do not incorporate full instrument panel illumination while also providing a backup or emergency power source.
Therefore a need exists in the art to provide a supplemental light source for older aircraft that is portable, light weight, cost effective, and provides an even illumination of all cockpit panel instruments. In addition, a need exists in the art for providing emergency cockpit panel illumination for older aircraft in the event of an in-flight electrical failure.
In accordance with the present invention, a portable lightweight unit comprises a DC to DC converter circuit, an array of LEDs, an emergency battery, and a method for maintaining emergency battery charge during non-emergency conditions. The present invention receives electrical power from either an external aircraft power source or from an internal emergency battery source. During normal operation, the primary power source is derived from a standard accessory power outlet inside the cockpit. Capable of operating over a wide range of aircraft voltages, the present invention is compatible with 12, 24, and 28 volt DC aircraft electrical systems. Primary power also maintains the internal battery""s charge for optimal battery power through the present invention""s internal regulator circuit In the event of an aircraft electrical system failure, the internal battery provides emergency power, and maintains instrument panel illumination. Instrument panel luminance is adjustable by controlling the amount of feedback voltage to the internal DC to DC buck type converter, which in turn changes the amount of constant current provided to the LED array.
The present invention corrects the problems associated with the single flood lamp method by providing a portable lightweight unit comprised of a DC to DC converter circuit with an array of multiple LEDs evenly distributed in a row. The distributed LED array results in an even illumination of the cockpit instrument panel without dark areas thus eliminating the need for a supplemental flashlight or similar prior art.
It is therefore an object of the invention to provide circuitry for of an IED a in a portable cockpit illumination device capable of operation from 12, 24, 28, and emergency battery voltages.
It is another object of the invention to provide emergency cockpit illumination that further provides an even illumination of the cockpit instrument panel, whereby all cockpit panel instruments are readily distinguished by the pilot.
It is another object of the invention to provide a portable cockpit illumination device as a bock up or supplement to existing aircraft light systems.
It is a further object of the invention to provide a lightweight, portable cockpit illumination device that can easily be installed or removed from an aircraft without the use of any tools.
The present invention is capable of operating over a wide range of standard aircraft voltages during normal operations, and provides emergency power from an internal battery during emergency operations, thus allowing the pilot to continue flying until a safe landing is possible.
The present invention also greatly increases the safety of night flying by keeping the pilot focused during an emergency, thus reducing the induced stress from a loss of cockpit lights.
The present invention quickly attaches inside the aircraft without the use of any tools or modifications to the aircraft, and can be easily removed for use in other aircraft. This feature is particularly useful to pilots who rent rather than own their aircraft.